1. Field of the Invention
The present invention relates to a power window control apparatus, and more particularly to a power window control apparatus preferably used in a vehicle, enhanced in precision of judging a foreign matter even if the foreign matter is caught by the vehicle window when driving to close the vehicle window of the vehicle.
2. Description of the Related Art
As a conventional power window apparatus, an opening and closing apparatus for vehicle disclosed in Japanese Patent Application Laid-open No. 5-95694 is known.
In this conventional apparatus, when driving a motor to raise or lower a vehicle window, a rotational angle of the motor is converted into a pulse signal by using an encoder, and the degree of opening of the vehicle window is detected by using a counting value of the pulse signal.
In this apparatus, for the pulse signal issued from the encoder while driving the motor, if the difference of pulse width between the previous value and present value is within a specified reference range over plural times consecutively, it is judged that a foreign matter is caught by the vehicle window. When thus judged, the ascending drive of the vehicle window is changed to descending drive, that is, it is controlled to drive by inverting the move of the vehicle window.
In this apparatus, therefore, if a foreign matter is caught by the vehicle window, it can be taken out immediately.
In this conventional apparatus, however, when driving the vehicle window, a load was applied to the engagement portions between the pinion gear for transmitting rotation of the motor and the sector gear for rotating the main arm for driving to move up or down the vehicle window.
As a result, fluctuated variation occur in the pulse width of the pulse signal issued from the encoder.
Or when the vehicle runs a rough road, vibrations due to rough road are further added to the engagement parts of the pinion gear and sector gear, and extreme fluctuations may occur in the pulse width of pulse signal issued from the encoder.
Consequently, although foreign matter is not caught in, it may be falsely judged that foreign matter has been caught in.
Moreover, if the difference is calculated by subtracting the present value from the previous value of the pulse width of pulse signal issued from the encoder, the fluctuated variation occurring in the pulse width cannot be erased, and taking such fluctuated value into consideration, it is necessary to set relatively wide the specified reference range about the difference of the previous value and present value of the pulse width for judging occurrence of foreign matter that is caught by the vehicle window.
As a result, it takes a time until it is actually detected from the time foreign matter is actually caught by, and hence the load applied to the motor is increased.